This invention relates to amorphous metallic alloys. More particularly, it relates to the enhancement of the magnetic properties of amorphous metallic alloys.
Amorphous metallic alloys, also sometimes referred to as "glassy metals", result when certain component materials are quenched from the molten state to the solid state at extremely high rates. For example, quenching at the rate of 10.sup.5 degrees per second has been found to result in an alloy which is substantially homogeneous and amorphous in form. That is, the rapid cooling prevents formation of a crystalline structure in the alloy material.
Until rather recently, the only known technology for the production of amorphous alloys utilized techniques such as vacuum evaporation, sputtering, electrodeposition, and the like. Also, the materials produced by those processes were not of convenient size or shape for extensive further development for some purposes, and any attempts to alter the shape destroyed their amorphous, homogeneous character.
More recently, however, production techniques have been developed whereby amorphous alloys may be synthesized in a convenient ribbon shape, and at a cost which appears to be quite economical. Consequently, considerable academic and industrial efforts are being undertaken to develop useful applications for the amorphous alloy materials.
It is a primary object of the present invention to provide useful applications for the class of amorphous magnetic metallic alloys.
Relevant properties of amorphous metallic alloys may be summarized briefly. Although homogeneous in composition, the amorphous alloys typically possess considerable strength, in contrast to conventional high strength alloys which consist of two or more phases. Rather than having standard stress-strain curve having a limited linear elastic range, followed by an elongated plastic strain region terminating at the ultimate strength, or breaking point, the amorphous alloys characteristically show a linear elastic region followed by a slightly nonlinear region ending at the breaking point. Amorphous alloys do not show the yield point behavior typical of crystalline alloys. The alloys do show some creep, the slow deformation which may occur over long periods of sustained loading. Magnetically, the alloys are "soft" materials, in that they possess relatively high permeability (i.e. the ratio of magnetic flux density produced in a medium to the magnetizing force producing it).
It is a more particular object of the present invention, in conformity with the foregoing properties of amorphous metallic alloys, to provide methods for enhancing the fundamental magnetic properties thereof, and further for utilizing the enhanced material in apparatus applications.
In a copending U.S. pat. application of C. D. Graham, T. Egami, and P. J. Flanders, Ser. No. 709,857 filed contemporaneously herewith and assigned to the assignee hereof, there is disclosed a method of enhancing the magnetic properties of amorphous magnetic metallic alloys by application of stress. However, in accordance with the methods taught therein, whenever the stress is removed, the magnetic properties of the alloy revert to their previous values.
It is accordingly a further object of the present invention to instill enhanced properties in amorphous metallic alloys, in such a manner that at least a portion of the enhanced characteristics become residual in the material.